Array substrate for fringe field switching mode liquid crystal display device and fringe field switching mode liquid crystal display device including the same

ABSTRACT

An array substrate for a fringe field switching mode liquid crystal display device includes a plurality of gate lines on a substrate; a gate insulating layer on the plurality of gate lines; a plurality of data lines on the gate insulating layer and crossing the plurality of gate lines to define a plurality of pixel regions; a thin film transistor electrically connected to the gate and data lines and in each pixel region; a pixel electrode having a plate shape and in the each pixel region, the pixel electrode connected to a portion of the thin film transistor; a first passivation layer on the pixel electrode and over the thin film transistor; and a common electrode on the first passivation layer and having a plurality of openings of a bar shape in the each pixel region, each of the openings having a major axis along the data line and a minor axis along the gate line, wherein a center portion of each opening overlaps the pixel electrode, and both ends along the major axis of each opening protrude beyond the pixel electrode.

The present application claims the benefit of Korean Patent ApplicationNos. 10-2008-0060328 and 10-2008-0082964, filed in Korea on Jun. 25,2008 and Aug. 25, 2008, respectively, all of which are herebyincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fringe field switching (FFS) modeliquid crystal display (LCD) device, and more particularly, to an arraysubstrate for an FFS mode LCD device capable of improving transmittanceand aperture ratio and an FFS mode LCD device including the arraysubstrate. The FFS mode LCD device can display a high quality image.

2. Discussion of the Related Art

A related art liquid crystal display (LCD) device uses opticalanisotropy and polarization properties of liquid crystal molecules. Theliquid crystal molecules have a definite alignment direction as a resultof their thin and long shapes. The alignment direction of the liquidcrystal molecules can be controlled by application of an electric fieldacross the liquid crystal molecules. As the intensity or direction ofthe electric field is changed, the alignment of the liquid crystalmolecules also changes. Since incident light is refracted based on theorientation of the liquid crystal molecules due to the opticalanisotropy of the liquid crystal molecules, images can be displayed bycontrolling light transmissivity.

Since the LCD device including a thin film transistor (TFT) as aswitching element, referred to as an active matrix LCD (AM-LCD) device,has excellent characteristics such as high resolution and display ofmoving images, the AM-LCD device has been widely used.

The AM-LCD device includes an array substrate, a color filter substrateand a liquid crystal layer interposed therebetween. The array substratemay include a pixel electrode and TFT, and the color filter substratemay include a color filter layer and a common electrode. The AM-LCDdevice is driven by an electric field between the pixel electrode andthe common electrode resulting in excellent properties of transmittanceand aperture ratio. However, since the AM-LCD device uses a verticalelectric field, the AM-LCD device has a bad viewing angle.

An in-plane switching (IPS) mode LCD device may be used to resolve theabove-mentioned limitations. FIG. 1 is a cross-sectional view of therelated art IPS mode LCD device. As shown in FIG. 1, the array substrateand the color filter substrate are separated and face each other. Thearray substrate includes a first substrate 10, a common electrode 17 anda pixel electrode 30. Though not shown, the array substrate may includea TFT, a gate line, a data line, for example. The color filter substrateincludes a second substrate 9, a color filter layer (not shown), forexample. A liquid crystal layer 11 is interposed between the firstsubstrate 10 and the second substrate 9. Since the common electrode 17and the pixel electrode 30 are formed on the first substrate 10 on thesame level, a horizontal electric field “L” is generated between thecommon and pixel electrodes 17 and 30.

FIGS. 2A and 2B are cross-sectional views showing turned on/offconditions of the related art IPS mode LCD device. As shown in FIG. 2A,when the voltage is applied to the IPS mode LCD device, liquid crystalmolecules 11 a above the common electrode 17 and the pixel electrode 30are unchanged. But, liquid crystal molecules 11 b between the commonelectrode 17 and the pixel electrode 30 are horizontally arranged due tothe horizontal electric field “L”. Since the liquid crystal moleculesare arranged by the horizontal electric field, the IPS mode LCD devicehas a characteristic of a wide viewing angle. FIG. 2B shows a conditionwhen the voltage is not applied to the IPS mode LCD device. Because anelectric field is not generated between the common and pixel electrodes17 and 30, the arrangement of liquid crystal molecules 11 is notchanged. However, the IPS mode LCD device has poor aperture ratio andtransmittance.

A fringe field switching (FFS) mode LCD device has been introduced toresolve the above-mentioned limitations. In the FFS mode LCD device, theliquid crystal molecules are driven by a fringe field.

FIG. 3 is a plan view of an array substrate for the related art FFS modeLCD device. As shown in FIG. 3, an array substrate includes a substrate41, a gate line 43, a data line 51, a thin film transistor (TFT) “Tr”, acommon electrode 75 and a pixel electrode 60. The gate line 43 and thedata line 51 are formed on the substrate 41 and cross each other todefine a pixel region “P”. The gate line 43 is insulated from the dataline 51 due to a gate insulating layer (not shown). The TFT “Tr” isformed in each pixel region “P” and connected to the gate and data lines43 and 51. The TFT “Tr” includes a gate electrode 45, the gateinsulating layer, a semiconductor layer (not shown), a source electrode55 and a drain electrode 58. The gate electrode 45 is connected to thegate line 43, and the source electrode 55 is connected to the data line51.

The pixel electrode 60 is formed in each pixel region “P”. The pixelelectrode 60 is electrically connected to the drain electrode 58 of theTFT “Tr” through a drain contact hole 59. The pixel electrode 60 has aplate shape and includes a plurality of openings “op”. Each of theopenings “op” has a bar shape. In addition, the common electrode 75having a plate shape is formed on an entire surface of a display regionof the substrate 41. The common electrode 75 overlaps the pixelelectrode 60. Although the common electrode 75 is formed on an entiresurface of the display region of the substrate 41, the common electrode75 corresponding to one pixel region “P” is marked by a dot-line.

In the array substrate for the FFS mode LCD device having the abovestructure, when voltages are applied to the common electrode 75 and thepixel electrodes 60, a fringe field is induced between the pixel andcommon electrodes 60 and 75.

In the above array substrate for the FFS mode LCD device, the openings“op” of the pixel electrode 60 perfectly overlaps the common electrode75. In this case, an uniform electric field is not generated at both endportions of the opening “op” along a major axis of the opening “op”. Theend portions, where non-uniform electric field is generated, may bereferred to as a disclination area “DA”. Namely, the liquid crystalmolecules in the disclination area “DA” have non-uniform arrangements.Since the FFS mode LCD device has a less transmittance in thedisclination area “DA” than other areas with an ON state, there are darkimages in the disclination area “DA”, as shown in FIG. 4 showing apicture showing a pixel region of an array substrate for the related artFFS mode LCD device.

The FFS mode LCD device has a decrease of transmittance and displayingquality due to the disclination area.

FIG. 5 is a plan view of the related art FFS mode LCD device. As shownin FIG. 5, the FFS mode LCD device 40 includes a first substrate 42, asecond substrate (not shown) and a liquid crystal layer (not shown)interposed therebetween.

On the first substrate 42, a gate line 44, a data line 52, a thin filmtransistor (TFT) “Tr”, a common electrode 76 and a pixel electrode 61are formed. The gate line 44 and the data line 52 are formed on thefirst substrate 42 and cross each other to define a pixel region “P”.The gate line 44 is insulated from the data line 52 due to a gateinsulating layer (not shown). The TFT “Tr” is formed in each pixelregion “P” and connected to the gate and data lines 44 and 52. The TFT“Tr” includes a gate electrode 46, the gate insulating layer, asemiconductor layer (not shown), a source electrode 56 and a drainelectrode 59. The gate electrode 46 is connected to the gate line 44,and the source electrode 56 is connected to the data line 52.

The pixel electrode 61 is formed in each pixel region “P”. The pixelelectrode 61 is electrically connected to the drain electrode 59 of theTFT “Tr”. The pixel electrode 61 has a plate shape and includes aplurality of openings “o”. Each of the openings “op” has a bar shape.The pixel electrode 61 is disposed inside of the pixel region “P”.Namely, the pixel electrode 61 does not overlap the gate and data lines44 and 52 and is spaced apart from the gate and data lines 44 and 52 bya predetermined distance. The reason why the pixel electrode does notoverlap the gate and data lines 44 and 52 is that there is a parasiticcapacitance between the gate line 44 the pixel electrode 61 and betweenthe data line 52 and the pixel electrode 61 such that a distortion in anelectrical field is generated when the pixel electrode overlaps the gateand data lines 44 and 52 with the gate insulating layer (not shown)therebetween. Accordingly, to prevent these problems, the pixelelectrode does not overlap the gate and data lines 44 and 52.

In addition, the common electrode 76 having a plate shape is formed onan entire surface of a display region of the first substrate 42. Thecommon electrode 76 overlaps the pixel electrode 61. Although the commonelectrode 76 is formed on an entire surface of the display region of thefirst substrate 42, the common electrode 76 corresponding to one pixelregion “P” is marked by a dot-line. The first substrate 42, where thegate line 44, the data line 52, the TFT “Tr”, the pixel electrode 61 andthe common electrode 76 are formed, may be referred to as an arraysubstrate.

In the array substrate for the FFS mode LCD device having the abovestructure, when voltages are applied to the common electrode 76 and thepixel electrodes 61, a fringe field is induced between the pixel andcommon electrodes 61 and 76.

On the second substrate (not shown) facing the first substrate 42, acolor filter layer (not shown) and a black matrix 85 are formed. Thecolor filter layer includes color filter patterns of red, green and bluecolors. The color filter patterns correspond to the pixel region “P”.The black matrix 85 is disposed to correspond to boundaries of the pixelregion “P”. Namely, the black matrix 85 corresponds to the gate line 44,the data line 52 and the TFT “Tr”.

In the above array substrate for the FFS mode LCD device, the openings“op” of the pixel electrode 60 perfectly overlaps the common electrode75. In this case, an uniform electric field is not generated at both endportions of the opening “op” along a major axis of the opening “op”. Theend portions, where non-uniform electric field is generated, may bereferred to as a disclination area “DA”. Namely, the liquid crystalmolecules in the disclination area “DA” have non-uniform arrangements.Since the FFS mode LCD device has a less transmittance in thedisclination area “DA” than other areas with an ON state, there are darkimages in the disclination area “DA”.

Since light is abnormally transmitted in the disclination area “DA”,there is a decrease of displaying quality. Accordingly, the black matrix85 extends to shield the disclination area “DA”. When the black matrix85 has wider area, there is a decrease in aperture ratio andtransmittance.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an array substrate foran FFS mode LCD device and an FFS mode LCD device including the samethat substantially obviate one or more of the problems due tolimitations and disadvantages of the related art.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. These andother advantages of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, anarray substrate for a fringe field switching mode liquid crystal displaydevice includes a plurality of gate lines on a substrate; a gateinsulating layer on the plurality of gate lines; a plurality of datalines on the gate insulating layer and crossing the plurality of gatelines to define a plurality of pixel regions; a thin film transistorelectrically connected to the gate and data lines and in each pixelregion; a pixel electrode having a plate shape and in the each pixelregion, the pixel electrode connected to a portion of the thin filmtransistor; a first passivation layer on the pixel electrode and overthe thin film transistor; and a common electrode on the firstpassivation layer and having a plurality of openings of a bar shape inthe each pixel region, each of the openings having a major axis alongthe data line and a minor axis along the gate line, wherein a centerportion of each opening overlaps the pixel electrode, and both endsalong the major axis of each opening protrude beyond the pixelelectrode.

In another aspect of the present invention, an array substrate for afringe field switching mode liquid crystal display device includes aplurality of gate lines on a substrate; a gate insulating layer on theplurality of gate lines; a plurality of data lines on the gateinsulating layer and crossing the plurality of gate lines to define aplurality of pixel regions; a thin film transistor electricallyconnected to the gate and data lines and in each pixel region; a pixelelectrode having a plate shape and in the each pixel region, the pixelelectrode connected to a portion of the thin film transistor; apassivation layer on the pixel electrode and over the thin filmtransistor; and a common electrode on the passivation layer and having aplurality of openings of a bar shape in the each pixel region, each ofthe openings having a major axis along the data line and a minor axisalong the gate line, wherein a center portion of each opening overlapsthe pixel electrode, and an end along the minor axis of an outermostopening of the plurality of openings protrudes beyond the pixelelectrode.

In another aspect of the present invention, an array substrate for afringe field switching mode liquid crystal display device includes aplurality of gate lines on a substrate; a gate insulating layer on theplurality of gate lines; a plurality of data lines on the gateinsulating layer and crossing the plurality of gate lines to define aplurality of pixel regions; a thin film transistor electricallyconnected to the gate and data lines and in each pixel region; a pixelelectrode having a plate shape and in the each pixel region, the pixelelectrode connected to a portion of the thin film transistor andoverlapping a portion of the gate line; a passivation layer on the pixelelectrode and over the thin film transistor; and a common electrode onthe passivation layer and having a plurality of openings of a bar shapein the each pixel region, each of the openings having a major axis alongthe data line and a minor axis along the gate line, wherein a centerportion of each opening overlaps the pixel electrode, and both endsalong the major axis of each opening overlap the gate line.

In another aspect of the present invention, an array substrate for afringe field switching mode liquid crystal display device includes aplurality of gate lines on a substrate; a gate insulating layer on theplurality of gate lines; a plurality of data lines on the gateinsulating layer and crossing the plurality of gate lines to define aplurality of pixel regions; a thin film transistor electricallyconnected to the gate and data lines and in each pixel region; a pixelelectrode having a plate shape and in the each pixel region, the pixelelectrode connected to a portion of the thin film transistor andoverlapping a portion of the gate line; a passivation layer on the pixelelectrode and over the thin film transistor; and a common electrode onthe passivation layer and having a plurality of openings of a bar shapein the each pixel region, each of the openings running across throughthe pixel regions along each data line.

In another aspect of the present invention, a fringe field switchingmode liquid crystal display device includes first and second substratefacing each other; a plurality of gate lines on the first substrate; agate insulating layer on the plurality of gate lines; a plurality ofdata lines on the gate insulating layer and crossing the plurality ofgate lines to define a plurality of pixel regions; a thin filmtransistor electrically connected to the gate and data lines and in eachpixel region; a pixel electrode having a plate shape and in the eachpixel region, the pixel electrode connected to a portion of the thinfilm transistor; a passivation layer on the pixel electrode and over thethin film transistor; a common electrode on the passivation layer andhaving a plurality of openings of a bar shape in the each pixel region,each of the openings having a major axis along the data line and a minoraxis along the gate line, wherein a center portion of each openingoverlaps the pixel electrode, and both ends along the major axis of eachopening protrude beyond the pixel electrode; a black matrix on thesecond substrate and surrounding the each pixel region; a color filterlayer on the second substrate and corresponding to the each pixelregion; and a liquid crystal layer between the first and secondsubstrates.

In another aspect of the present invention, a fringe field switchingmode liquid crystal display device includes first and second substratefacing each other; a plurality of gate lines on the first substrate; agate insulating layer on the plurality of gate lines; a plurality ofdata lines on the gate insulating layer and crossing the plurality ofgate lines to define a plurality of pixel regions; a thin filmtransistor electrically connected to the gate and data lines and in eachpixel region; a pixel electrode having a plate shape and in the eachpixel region, the pixel electrode connected to a portion of the thinfilm transistor; a passivation layer on the pixel electrode and over thethin film transistor; a common electrode on the passivation layer andhaving a plurality of openings of a bar shape in the each pixel region,each of the openings having a major axis along the data line and a minoraxis along the gate line, wherein a center portion of each openingoverlaps the pixel electrode, and an end along the minor axis of anoutermost opening of the plurality of openings protrudes beyond thepixel electrode; a black matrix on the second substrate and surroundingthe each pixel region; a color filter layer on the second substrate andcorresponding to the each pixel region; and a liquid crystal layerbetween the first and second substrates.

In another aspect of the present invention, a fringe field switchingmode liquid crystal display device includes first and second substratefacing each other; a plurality of gate lines on the first substrate; agate insulating layer on the plurality of gate lines; a plurality ofdata lines on the gate insulating layer and crossing the plurality ofgate lines to define a plurality of pixel regions; a thin filmtransistor electrically connected to the gate and data lines and in eachpixel region; a pixel electrode having a plate shape and in the eachpixel region, the pixel electrode connected to a portion of the thinfilm transistor and overlapping a portion of the gate line; apassivation layer on the pixel electrode and over the thin filmtransistor; a common electrode on the first passivation layer and havinga plurality of openings of a bar shape in the each pixel region, each ofthe openings having a major axis along the data line and a minor axisalong the gate line, wherein a center portion of each opening overlapsthe pixel electrode, and both ends along the major axis of each openingoverlap the gate line; a black matrix on the second substrate andshielding the data lines and the thin film transistor except the gatelines; a color filter layer on the second substrate and corresponding tothe each pixel region; and a liquid crystal layer between the first andsecond substrates.

In another aspect of the present invention, a fringe field switchingmode liquid crystal display device includes first and second substratefacing each other; a plurality of gate lines on the first substrate; agate insulating layer on the plurality of gate lines; a plurality ofdata lines on the gate insulating layer and crossing the plurality ofgate lines to define a plurality of pixel regions; a thin filmtransistor electrically connected to the gate and data lines and in eachpixel region; a pixel electrode having a plate shape and in the eachpixel region, the pixel electrode connected to a portion of the thinfilm transistor and overlapping a portion of the gate line; apassivation layer on the pixel electrode and over the thin filmtransistor; a common electrode on the first passivation layer and havinga plurality of openings of a bar shape in the each pixel region, each ofthe openings running across through the pixel regions along each dataline; a black matrix on the second substrate and shielding the datalines and the thin film transistor except the gate lines; a color filterlayer on the second substrate and corresponding to the each pixelregion; and a liquid crystal layer between the first and secondsubstrates.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a cross-sectional view of the related art IPS mode LCD device.

FIGS. 2A and 2B are cross-sectional views showing turned on/offconditions of the related art IPS mode LCD device.

FIG. 3 is a plan view of an array substrate for the related art FFS modeLCD device.

FIG. 4 shows a picture showing a pixel region of an array substrate forthe related art FFS mode LCD device

FIG. 5 is a plan view of the related art FFS mode LCD device.

FIG. 6 is a plan view of an array substrate for an FFS mode LCD deviceaccording to a first embodiment of the present invention.

FIG. 7 is a cross-sectional view taken along the line VI-VI of FIG. 6.

FIG. 8 is a cross-sectional view taken along the line VII-VII of FIG. 6.

FIG. 9 is a cross-sectional view taken along the line VIII-VIII of FIG.6.

FIG. 10 is a plan view of an array substrate for an FFS mode LCD deviceaccording to a modified embodiment of the first embodiment of thepresent invention.

FIG. 11 is a plan view of an array substrate for an FFS mode LCD deviceaccording to a second embodiment of the present invention.

FIG. 12 is a plan view of an array substrate for an FFS mode LCD deviceaccording to a modified embodiment of the second embodiment of thepresent invention.

FIG. 13 is a plan view of an FFS mode LCD device according to a thirdembodiment of the present invention.

FIG. 14 is a cross-sectional view taken along the line XIV-XIV of FIG.13.

FIG. 15 is a cross-sectional view taken along the line XV-XV of FIG. 13.

FIG. 16 is a plan view of an FFS mode LCD device according to a modifiedembodiment of the third embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments,examples of which are illustrated in the accompanying drawings.

FIG. 6 is a plan view of an array substrate for an FFS mode LCD deviceaccording to a first embodiment of the present invention, and FIG. 7 isa cross-sectional view taken along the line VI-VI of FIG. 6. FIG. 8 is across-sectional view taken along the line VII-VII of FIG. 6, and FIG. 9is a cross-sectional view taken along the line VIII-VIII of FIG. 6. Adisplay region, where a plurality of pixel region are formed, anon-display region, where a pad region is formed, and a switchingregion, where a TFT as a switching element is formed, are respectivelydefined on the array substrate. The non-display region is disposed at aperiphery of the display region, and the switching region is disposed inthe pixel region.

In FIG. 5, a gate line 105 is formed on a substrate 101 along a firstdirection. A data line 130 along a second direction crosses the gateline 105 such that a pixel region “P” is defined.

In the pixel region “P”, a TFT “Tr” connected to the gate and data lines105 and 130 is formed. The TFT “Tr” includes a gate electrode 108, agate insulating layer (not shown), a semiconductor layer (not shown)including an active layer (not shown) of intrinsic amorphous silicon andan ohmic contact layer (not shown) of impurity-doped amorphous silicon,a source electrode 133 and a drain electrode 136. The source electrode133 is spaced apart from the drain electrode 136. In FIG. 5, to improveaperture ratio, the gate electrode 108 is a portion of the gate line 105such that the TFT “Tr” is formed on the gate line 105. However, the gateelectrode 105 may protrude from the gate line 105 into the pixel region“P”.

A pixel electrode 155 having a plate shape is disposed in the pixelregion “P”. The pixel electrode 155 is connected to the drain electrode136 of the TFT “Tr” through the drain contact hole 150. In addition, acommon electrode 170 having a plurality of openings “op” is formed on anentire surface of the display region. Each of the openings “op” has abar shape. The common electrode 170 corresponding to one pixel region“P” is marked by a dot-line.

The openings “op” is positioned in the pixel region “P” to overlap thepixel electrode 155. Each opening “op” has a major axis along the dataline 130 and a minor axis along the gate line 105. A center portion ofthe opening “op” overlaps the pixel electrode 155, while both ends alongthe major axis of the opening “op” protrude beyond the pixel electrode155. Namely, the both ends along the major axis of the opening “op” areshown to be positioned outside of the pixel electrode 155, and otherportions of the opening “op” are shown to be positioned inside of thepixel electrode 155. Each opening “op” of the common electrode 170 has amajor length greater than the pixel electrode 155 such that the bothends of the opening “op” along the major axis do not overlap the pixelelectrode 155. To the above structure, the openings should be formed onthe common electrode, not the pixel electrode. The common electrode 170covers the TFT “Tr” in FIG. 6. However, a portion of the commonelectrode 170 corresponding to the TFT “Tr” may be removed such that aportion of the second passivation layer 160 is exposed.

In the both ends of the opening “op” along the major axis, an electricfield is not generated or is very weak at a minor side surface of theopening “op”. Liquid crystal molecules at the both ends of the opening“op” along the major axis are driven by an electric field generated at amajor side surface of the opening “op” to have an uniform arrangement.As a result, the disclination area “DA” (of FIG. 3) show in the relatedart FFS mode LCD device may be not generated in the FFS mode LCD deviceaccording to the present invention. Or, even if there is thedisclination area in the FFS mode LCD device, there is no decrease inaperture ratio because the disclination area overlaps the gate line 105.Accordingly, the FFS mode LCD device has improved aperture ratio andtransmittance.

Referring to FIG. 10, which is a plan view of an array substrate for anFFS mode LCD device according to a modified embodiment of the firstembodiment of the present invention, openings “op” in pixel regionsadjacent to each other along the data line 130 are connected to eachother. Namely, the openings “op” in pixel regions adjacent to each otheralong the data line 130 runs across the gate line 105. The openings “op”are formed throughout the pixel regions “P” arranged along the singledata line 130 and a single stripe shape. The FFS mode LCD deviceaccording to the modified embodiment of the first embodiment also hasimproved aperture ratio and transmittance.

Since there is no end of the opening “op” the pixel region “P” except apixel region “P” in edges of the display region, there is no electricfield by a minor side surface of the opening “op”. Accordingly, theliquid crystal molecules at all surface of the pixel region “P” has anuniform arrangement. Moreover, an end along the major axis of theopening in outermost pixel regions (not shown) protrudes beyond thepixel electrode such that a generation of the disclination area can beprevented or minimized.

Referring to FIGS. 7 to 9, a cross-sectional structure of the arraysubstrate for the FFS mode LCD device according to the first embodiment,of the present invention is explained. The array substrate for the FFSmode LCD device has a difference in a cross-sectional structure alongthe line VIII-VIII with compared the array substrate for FFS mode LCDdevice according to the first embodiment.

In FIGS. 7 to 9, the array substrate for the FFS mode LCD deviceaccording to the first embodiment of the present invention includes thegate line 105 and the gate electrode 108 on the substrate 101. Thesubstrate 101 may be transparent. Each of the gate line 105 and the gateelectrode 108 is formed of a metallic material having a low resistanceproperty. For example, the metallic material may include one of aluminum(Al), Al alloy (AlNd), copper (Cu), Cu alloy, chrome (Cr) and molybdenum(Mo). The gate electrode 108 is connected to the gate line 105 anddisposed in the switching region “TrA”.

Although each of the gate line 105 and the gate electrode 108 has asingle-layered structure in FIGS. 7 and 9, each of the gate line 105 andthe gate electrode 108 may have a double-layered structure. In thiscase, a lower layer of the double-layered structure may be formed of ametallic material having a low resistance property, such as Al, Alalloy, Cu and Cu alloy, and an upper layer of the double-layeredstructure may be formed of Mo.

On the gate line 105 and the gate electrode 108, a gate insulating layer115 is formed of an inorganic insulating material such as silicon oxide(SiO₂) and silicon nitride (SiNx). The semiconductor layer 120 includingthe active layer 120 a of intrinsic amorphous silicon and the ohmiccontact layer 120 b of impurity-doped amorphous silicon is formed on thegate insulating layer 115 and in the switching region “TrA”. The sourceand drain electrodes 133 and 136 spaced apart from each other are formedon the semiconductor layer 120. A portion of the ohmic contact layer 120b is etched such that a portion of the active layer 120 a is exposedbetween the source and drain electrodes 133 and 136.

In addition, the data line 130, which crosses the gate line 105 todefine the pixel region “P”, is formed on the gate insulating layer 115.The source electrode 133 of the TFT “Tr” is connected to the data line130.

A semiconductor pattern 121 including first and second patterns 121 aand 121 b is disposed between the data line 130 and the gate insulatinglayer 115. The semiconductor pattern 121 is formed of the same materialas the semiconductor layer 120. Whether the semiconductor pattern 121 isformed or not is determined by a fabricating method.

Namely, when the semiconductor layer 120, the data line 130 and thesource and drain electrodes 133 and 136 are formed by a single maskprocess, there is the semiconductor pattern 121 under the data line 130,as shown in FIG. 8. However, if the semiconductor layer 120 is formed bya mask process different from a mask process for the data line 130 andthe source and drain electrodes 133 and 136, there is no semiconductorpattern 121 under the data line 130.

A first passivation layer 140 covering the data line 130 and the TFT“Tr” is formed of one of an inorganic insulating material and an organicinsulating material. The inorganic insulating material includes one ofsilicon oxide (SiO2) and silicon nitride (SiNx), and the organicinsulating material includes one of benzocyclobuten (BCB) andphoto-acryl. In FIGS. 7 to 9, since the first passivation layer 140 isformed an inorganic insulating material, the first passivation layer 140has a step difference. However, when the first passivation layer 140 isformed an organic insulating material, the first passivation layer 140has a flat top surface. The first passivation layer 140 has a draincontact hole 150 exposing a portion of the drain electrode 136 of theTFT “Tr”.

The pixel electrode 155 having a plate shape is formed in each pixelregion “P” and on the first passivation layer 140 having the draincontact hole 150. The pixel electrode 155 contacts the drain electrode136 through the drain contact hole 150 and is formed of a transparentconductive material such as indium-tin-oxide (ITO) and indium-zinc-oxide(IZO).

On the other hand, the pixel electrode 155 may directly contact thedrain electrode 136 of the TFT “Tr” and disposed directly on the gateinsulating layer 115. In this case, the first passivation layer 140having the drain contact hole 150 may be omitted.

A second passivation layer 160 is formed on the pixel electrode 155. Thesecond passivation layer 160 is formed of one of the inorganicinsulating material and an organic insulating material. The commonelectrode 170 of the transparent conductive material is formed on thesecond passivation layer 160 and on an entire surface of the displayregion of the substrate 101. The common electrode 170 has a plate shapeand a plurality of openings “op” spaced apart from each other in eachpixel region “P”. Each opening “op” has a bar shape and has a major axisalong the data line 130. The major length of the opening “op” is greaterthan that of the pixel electrode 155. Accordingly, a center portion ofthe opening “op” overlaps the pixel electrode 155, while both ends alongthe major axis of the opening “op” protrude beyond the pixel electrode155. In other word, each end along the major axis of the opening “op” ismuch adjacent to the gate line 105 than the pixel electrode 155.

In the array substrate for the FFS mode LCD device according to themodified embodiment of the first embodiment, the opening “op” extends torun across the adjacent pixel regions “P” along the data line 130.Namely, the opening “op” has a single stripe shape at an entire of thedisplay region. Accordingly, the common electrode is not shown in FIG.8. In this case, since there is an end along the major axis of theopening in outermost pixel region (not shown), the end along the majoraxis of the opening in outermost pixel regions (not shown) protrudesbeyond the pixel electrode.

There are three openings “op” in each pixel region “P”. Moreover, theopenings “op” are spaced apart from each other by the same distance.However, to obtain an efficient fringe field, the common electrode 170may have two to ten openings “op”.

In the non-display region at a periphery of the display region, thereare gate pad region (not shown) and the data pad region (not shown). Inthe gate pad region, a gate pad electrode (not shown) connected to thegate line 105 is disposed. In the data pad region, a data pad electrode(not shown) connected to the data line 130 is disposed. In addition, acommon pad electrode (not shown) connected to the common electrode 170for applying a common voltage into the common electrode 170 is formed inthe non-display region.

The gate insulating layer 115 and the first and second passivationlayers 140 and 160 on the gate pad electrode are removed such that agate pad contact hole (not shown) exposing the gate pad electrode isformed. The first and second passivation layers 140 and 160 on the datapad electrode are removed such that a data pad contact hole (not shown)exposing the data pad electrode is formed.

In addition, a gate auxiliary pad electrode (not shown) contacting thegate pad electrode through the gate pad contact hole is formed on thesecond passivation layer 160 and in the gate pad region. A dataauxiliary pad electrode (not shown) contacting the data pad electrodethrough the data pad contact hole is formed on the second passivationlayer 160 and in the gate pad region. Each of the gate and dataauxiliary pad electrodes is formed of the same material as the commonelectrode 170. The common pad electrode is disposed in one of the gatepad region and the data pad region. The common pad electrode extendsfrom the common electrode 170 as a line shape.

In an array substrate for an FFS mode LCD device according to a secondembodiment of the present invention, there is only difference in apositional relation between an opening in a common electrode and a pixelelectrode. Accordingly, an explanation is focused on the differences.

Although not shown, the above array substrate is attached with a colorfilter substrate including a black matrix and a color filter layer suchthat an FFS mode LCD device is obtained.

FIG. 11 is a plan view of an array substrate for an FFS mode LCD deviceaccording to a second embodiment of the present invention. Although onlyboth ends along the major axis of the opening “op” in the commonelectrode are shown to be positioned outside the pixel electrode in FIG.6, not only both ends along a major axis of an opening “op” in a commonelectrode 270 but also an end along a minor axis of an outermostopenings “op1” in each pixel region “P” is shown to be positionedoutside a pixel electrode 255 in FIG. 11. Namely, the end along theminor axis of the outermost openings “op1” in each pixel region “P”protrudes beyond the pixel electrode 255. Ends of the minor axis ofother openings “op2” in center of the pixel region “P” is not protrudethe pixel electrode 255 and overlaps the pixel electrode 255.

The reason why the end along the minor axis of the outermost openings“op1” in each pixel region “P” protrudes beyond the pixel electrode 255is that an uniform fringe field along a center of the pixel-region “P”is generated at the outermost opening “op1”. As a result, an electricfield by a fringe field is not generated or is very weak at theoutermost opening “op1”.

On the other hand, referring to FIG. 12, which is a plan view of anarray substrate for an FFS mode LCD device according to a modifiedembodiment of the second embodiment of the present invention, both endsalong a major axis of the openings “op1” and “op2” in each pixel region“P” overlaps the pixel electrode 255, while an end along a minor axis ofthe outermost opening “op1” is positioned to be disposed outside of thepixel electrode 255. Namely, each of the openings “op1” and “op2” has amajor axial length smaller than the pixel electrode. As a result, thecenter opening “op2” completely overlap the pixel electrode 255.However, the end along the minor axis of the outermost opening “op1”protrudes beyond the pixel electrode 255.

Similar to the modified embodiment of the first embodiment shown in FIG.10, in the array substrate for the FFS mode LCD device according to thesecond embodiment and the array substrate for the FFS mode LCD deviceaccording to the modified embodiment of the second embodiment, theopenings “op1” and “op2” may run across the pixel regions along eachdata line 230.

Although not shown, the above array substrate is attached with a colorfilter substrate including a black matrix and a color filter layer suchthat an FFS mode LCD device is obtained.

Hereinafter, a fabricating method of the array substrate for the FFSmode LCD device according to the first embodiment is briefly explainedwith reference to FIGS. 6 to 9. The second embodiment and the modifiedembodiment of the second embodiment have a difference in a positionalrelation between the opening of the common electrode and the pixelelectrode. Accordingly, the explanation of the fabricating process isfocused on the first embodiment. A switching region “TrA” where a TFT“Tr” is formed is defined in each pixel region “P”.

First, a first metallic material having a low resistance property is onthe substrate 101 to form a first metal layer (not shown). For example,the first metallic material include one of aluminum (Al), Al alloy(AlNd), copper (Cu), Cu alloy, chrome (Cr) and molybdenum (Mo). Thefirst metal layer is patterned by a mask process to form the gate line105 along a first direction and the gate electrode 108 in the switchingregion “TrA”. The gate electrode 108 is connected to the gate line 105.The mask process includes a step of coating a photoresist (PR) layer onthe first metal layer, a step of exposing the PR layer using a mask, astep of developing the exposed PR layer to form a PR pattern, a step ofetching the first metal layer using the PR pattern as an etching maskand stripping remained the PR pattern. At the same time, the gate padelectrode (not shown) connected to an end of the gate line 105 is formedin the gate pad region (not shown).

Although the gate line 105 and the gate electrode 108 having asingle-layered structure are shown, each of the gate line 105 and thegate electrode 108 may have a double-layered structure. For example, alower layer of the double-layered structure may be formed of Al alloy,and an upper layer of the double-layered structure may be formed of Mo.

Next, the gate insulating layer 115 is formed on the gate line 105 andthe gate electrode 108 by depositing an inorganic insulating materialsuch as silicon oxide (SiO₂) and silicon nitride (SiNx). Next, anintrinsic amorphous silicon layer (not shown), an impurity-dopedamorphous silicon layer (not shown) and a second metal layer (not shown)are sequentially stacked on the gate insulating layer 115. The secondmetal layer is formed by depositing one of aluminum (Al), Al alloy(AlNd), copper (Cu) and Cu alloy. Then, a PR layer (not shown) is formedon the second metal layer, and the PR layer is developed by a half-toneexposing method or a refractive exposing method to form first and secondPR patterns (not shown) having a difference in a thickness.

Next, the second metal layer exposed by the first and second PRpatterns, and the impurity-doped amorphous silicon layer and theintrinsic amorphous silicon layer under the exposed second metal layerare sequentially etched to form the data line 130 along a seconddirection. The data line 130 crosses the gate line 105 to define thepixel region “P”. At the same time, the active layer 120 a, an ohmiccontact pattern (not shown) and a source-drain pattern (not shown) arestacked on the gate insulating layer 115 and in the switching region“TrA”. Moreover, the data pad electrode (not shown) connected to an endof the data line 130 is formed in the data pad region (not shown).

Next, an ashing process is performed to remove the second PR patternhaving a smaller thickness than the first PR pattern. A center portionof the source-drain pattern is exposed by removing the second PRpattern. The center portion of the source-drain pattern and a portion ofthe ohmic contact pattern under the center portion of the source-drainpattern are etched to form the source and drain electrodes 133 and 136and the ohmic contact layer 120 b under the source and drain electrodes133 and 136. A portion of the active layer 120 a is exposed. The gateelectrode 108, the gate insulating layer 115, the semiconductor layer120 including the active layer 120 a and the ohmic contact layer 120 b,the source electrode 133 and the drain electrode 136 constitute the TFT“Tr” in the switching region “TrA”. Since the semiconductor layer 120and the source and drain electrodes 133 and 136 are formed by a singlemask process, there is the semiconductor pattern 121 including the firstand second patterns 121 a and 121 b, which are respectively formed ofthe same material as the active layer 120 a and the ohmic contact layer120 b, under the data line 130 formed of the same material and on thesame layer as the source and drain electrodes 133 and 136.

On the other hand, the semiconductor layer 120 may be formed by a maskprocess different from the source and drain electrodes 133 and 136.Namely, the semiconductor layer 120 and the source and drain electrodes133 and 136 may be formed by two mask processes. In this case, theintrinsic amorphous silicon layer and the impurity-doped amorphoussilicon layer stacked on the gate insulating layer are etched by onemask process to form the active layer 120 a and the ohmic contactpattern. Then, the second metal layer is formed on the ohmic contactpattern. Next, the second metal layer is patterned by another maskprocess to form the data line 130, the source electrode 133 and thedrain electrode 136, and a portion of the ohmic contact pattern exposedbetween the source and drain electrodes 133 and 136 is removed to exposea portion of the active layer 120 a and form the ohmic contact layer 120b. In this case, there is no semiconductor pattern under the data line130.

Next, an inorganic insulating material, such as silicon oxide (SiO2) andsilicon nitride (SiNx), is deposited or an organic insulating material,such as benzocyclobutene (BCB) and photo-acryl, is coated on the TFT“Tr” and the data line 130 to form the first passivation layer 140.Then, the first passivation layer 140 is patterned to form the draincontact hole 150 exposing a portion of the drain electrode 136. Asmentioned above, the first passivation layer 140 may be omitted.

Next, a transparent conductive material, such as ITO and IZO, isdeposited on the first passivation layer 140 including the drain contacthole 150 to form a first transparent conductive material layer. Thefirst transparent conductive material layer is patterned by a maskprocess to form the pixel electrode 155 having a plate shape andconnected to the drain electrode 136 through the drain contact hole 150.If the first passivation layer 140 is omitted, the pixel electrode 155is disposed directly on the gate insulating layer 115 and directlycontacts the drain electrode 136.

Next, an inorganic insulating material, such as silicon oxide (SiO2) andsilicon nitride (SiNx), is deposited or an organic insulating material,such as benzocyclobutene (BCB) and photo-acryl, is coated on the pixelelectrode 155 to form the second passivation layer 160.

The second passivation layer 160, the first passivation layer 140 andthe gate insulating layer 115 in the gate pad region are removed to formthe gate pad contact hole (not shown) exposing the gate pad electrode.In addition, the second passivation layer 160 and the first passivationlayer 140 in the data pad region are removed to form the data padcontact hole (not shown) exposing the data pad electrode.

Next, a transparent conductive material, such as ITO and IZO, isdeposited on the second passivation layer 160 including the gate padcontact hole and the data pad contact hole to form a second transparentconductive material layer. The second transparent conductive materiallayer is patterned by a mask process to form the common electrode 170 inan entire surface of the display region. The common electrode 170 has aplate shape. At the same time, the gate auxiliary pad electrode (notshown) contacting the gate pad electrode through the gate pad contacthole is formed in the gate pad region, and the data auxiliary padelectrode (not shown) contacting the data pad electrode through the datapad contact hole is formed in the data pad region. The common electrode170 has openings as shown in FIGS. 5, 9, 10 and 11.

FIG. 13 is a plan view of an FFS mode LCD device according to a thirdembodiment of the present invention, FIG. 14 is a cross-sectional viewtaken along the line XIV-XIV of FIG. 13, and FIG. 15 is across-sectional view taken along the line XV-XV of FIG. 13. Forconvenience of explanation, a region where a plurality of pixel regionsis defined as a display region.

In FIG. 13, an FFS mode LCD device 300 includes a first substrate 301, asecond substrate (not shown) facing the first substrate 301 and a liquidcrystal layer (not shown) interposed therebetween.

On the first substrate 301, a gate line 305 is formed along a firstdirection. A data line 330 along a second direction crosses the gateline 305 such that a pixel region “P” is defined.

In the pixel region “P”, a TFT “Tr” connected to the gate and data lines305 and 330 is formed. The TFT “Tr” includes a gate electrode 308, agate insulating layer (not shown), a semiconductor layer (not shown)including an active layer (not shown) of intrinsic amorphous silicon andan ohmic contact layer (not shown) of impurity-doped amorphous silicon,a source electrode 333 and a drain electrode 336. The source electrode333 is spaced apart from the drain electrode 336. In FIG. 13, to improveaperture ratio, the gate electrode 308 is a portion of the gate line 305such that the TFT “Tr” is formed on the gate line 305. However, the gateelectrode 305 may protrude from the gate line 305 into the pixel region“P”.

A pixel electrode 355 having a plate shape is disposed in the pixelregion “P”. The pixel electrode 355 is connected to the drain electrode336 of the TFT “Tr”. The pixel electrode 355 overlaps a portion of aprevious gate line 305. When the gate line 305 has a second width “t2”,the overlapped portion of the pixel electrode 355 and the previous gateline 305 has a first width “t1” with range less than about 50percentages (%) of the second width “t2”. Namely, the second width “t2”is equal to or smaller than a half of the first width “t1”. The secondwidth “t2” of the gate line 305 may be about 8 micrometers to about 12micrometers, and the first width “t1” of the overlapped portion of thepixel electrode 355 and the previous gate line 305 may be about 4micrometers to about 6 micrometers. The reason why the second width “t2”is equal to or smaller than a half of the first width “t1” is that adistortion in an electric field generated from a coupling problem inadjacent pixel electrodes 305 is to be prevented. In the related art FFSmode LCD device, the pixel electrode is disposed inside the pixel regionto prevent a distortion in an electric field generated from a couplingproblem in adjacent pixel electrodes. However, by a simulation, it isknow that a distortion in an electric field generated from a parasiticcapacitance between the overlapped pixel electrode 355 and theoverlapped previous gate line 305 or a coupling problem in adjacentpixel electrodes 355 is scarcely generated. Considering the simulationresult, in the FFS mode LCD device according to the present invention,the second width “t2” of the overlapped portion between the pixelelectrode 355 and the gate line 305 is equal to or smaller than a halfof the first width “t1” of the gate line 305.

In addition, a common electrode 370 having a plurality of openings “op”in each pixel region is formed on an entire surface of the firstsubstrate 301. The openings “op” overlap the pixel electrode 355 and hasa bar shape. The common electrode 370 corresponding to one pixel region“P” is marked by a dot-line.

The opening “op” has a major axis along the data line 330 and a minoraxis along the gate line 305. Both ends along the major axis of theopening “op” overlap a portion of the gate lines 305. Each of theopenings “op” has a relatively great major axial length such that theFFS mode LCD device has improved transmittance.

Since the both ends along the major axis of the opening “op” overlap theportion of the gate lines 305, light can not pass the both ends.Accordingly, even if a disclination area is generated at the ends alongthe major axis of the opening “op”, there is no decrease in displayingquality because the disclination area is shield by the gate line 305.

On the other hand, referring to FIG. 16, which is a plan view of an FFSmode LCD device according to a modified embodiment of the thirdembodiment of the present invention, each opening “op” runs across pixelregions “P” along a data line 330. Namely, each opening “op” in thecommon electrode 370 has a single stripe shape through an entire of thedisplay region along the data line 330.

In the FFS mode LCD device in FIG. 16, there is only one end along amajor axis of the opening “op” in an outermost pixel region (not shown)of the display region. Accordingly, there is no electric field by ashort end side along the major axis of the opening “op” in the centralpixel regions “P” except the outermost pixel region (not shown). Theliquid crystal molecules in the central pixel region “P” is driven by anelectric field generated by a long end side along the major axis of theopening “op” such that the liquid crystal molecules have an uniform anddesired arrangement.

As a result, since the disclination area is not generated, the FFS modeLCD device has improved transmittance and aperture ratio. Even if thedisclination area is generated, the gate line 305, which overlaps thedisclination area, shields the disclination area such that the FFS modeLCD device has improved transmittance and aperture ratio.

Referring again to FIG. 13, although the common electrode 370 includingthe openings “op” of a bar shape covers an entire of the display region,the common electrode 370 may have another opening (not shown)corresponding to the TFT “Tr” to prevent a parasitic capacitancegenerated between the gate electrode 308 of the TFT “Tr” and the commonelectrode 370 when the common electrode 370 overlapping the TFT “Tr”.The parasitic capacitance may have a bad effect on a switching operationof the TFT “Tr”.

The above first substrate 301 including the gate line 305, the data line330, the TFT “Tr”, the pixel electrode 355 and the common electrode 370may be referred to as an array substrate.

On the second substrate (not shown) facing the first substrate 301, acolor filter layer (not shown), a black matrix 384 and an overcoat layer(not shown) are formed. The color filter layer includes color filterpatterns of red, green and blue colors and corresponds to each pixelregion “P” of the first substrate 301. The black matrix 384 correspondsto the data line 330 the TFT “Tr”. The overcoat layer is formed on thecolor filter layer. In addition, the liquid crystal layer is disposedbetween the first substrate 301 and the second substrate.

The black matrix in the related are FFS mode LCD device corresponds tothe gate line as well as the data line and the TFT. Namely, the blackmatrix surrounds the each pixel region. However, since the black matrix384 in the FFS mode LCD device according to the present inventioncorresponds to the data line 330 and the TFT “Tr” except the gate line305, an aperture ratio of the FFS mode LCD device is further improved.

In the FFS mode LCD device according to the present invention, the pixelelectrode 355 overlaps the previous gate line 305 with a predeterminedwidth. In addition, the ends along the major axis of the opening “op” inthe common electrode 370 also overlap the gate line 305 as shown in FIG.13. Or, the opening “op” of a single stripe shape runs across the pixelregions “P” along the data line 330 as shown in FIG. 16. As a result,the disclination area at the ends along the major axis of the opening“op” is not generated or is minimized. Accordingly, even if the blackmatrix 384 does not shield the gate line 305, there is no problem in adisplaying quality.

A cross-sectional structure of an FFS mode LCD device according to thethird embodiment of the present invention is explained with reference toFIGS. 14 and 15. Since the FFS mode LCD device according to the modifiedembodiment of the third embodiment of the present invention only has adifference in a positional relation of the gate line and the opening inthe common electrode, the explanation is focused on the FFS mode LCDdevice according to the third embodiment. For convenience ofexplanation, a region, where the TFT is formed, is defined as aswitching region in the pixel region.

In FIGS. 14 and 15, the array substrate for the FFS mode LCD device 300includes the first substrate 301. The substrate 301 may be transparent.The gate line 305 and the gate electrode 308 are formed on the substrate301. Each of the gate line 305 and the gate electrode 308 is formed of ametallic material having a low resistance property. For example, themetallic material may include one of aluminum (Al), Al alloy (AlNd),copper (Cu) and Cu alloy. The gate electrode 308 is connected to thegate line 305 and disposed in the switching region “TrA”.

Although each of the gate line 305 and the gate electrode 308 has asingle-layered structure in FIGS. 14 and 15, each of the gate line 305and the gate electrode 308 may have a double-layered structure. In thiscase, a lower layer of the double-layered structure may be formed of ametallic material having a low resistance property, such as Al, Alalloy, Cu and Cu alloy, and an upper layer of the double-layeredstructure may be formed of Mo.

On the gate line 305 and the gate electrode 308, a gate insulating layer315 is formed of an inorganic insulating material such as silicon oxide(SiO₂) and silicon nitride (SiNx).

The semiconductor layer 320 including the active layer 320 a ofintrinsic amorphous silicon and the ohmic contact layer 320 b ofimpurity-doped amorphous silicon is formed on the gate insulating layer315 and in the switching region “TrA”. The source and drain electrodes333 and 336 spaced apart from each other are formed on the semiconductorlayer 320. A portion of the ohmic contact layer 320 b is etched suchthat a portion of the active layer 320 a is exposed between the sourceand drain electrodes 333 and 336. Each of the source and drainelectrodes 333 and 336 may be formed of a metallic material, suchmolybdenum (Mo), Chrome (Cr), aluminum (Al), Al alloy (AlNd), copper(Cu) and Cu alloy. The gate electrode 308, the gate insulating layer315, the semiconductor layer 320, the source electrode 333 and the drainelectrode 336 constitute the TFT “Tr” in the switching region “TrA”.

In addition, the data line 330, which crosses the gate line 305 todefine the pixel region “P”, is formed on the gate insulating layer 315.The source electrode 333 of the TFT “Tr” is connected to the data line330. Each of the data line 330, the source electrode 333 and the drainelectrode 336 may have a double-layered structure.

A semiconductor pattern 321 including first and second patterns 321 aand 321 b is disposed between the data line 330 and the gate insulatinglayer 315. The semiconductor pattern 321 is formed of the same materialas the semiconductor layer 320. Whether the semiconductor pattern 321 isformed or not is determined by a fabricating method.

Namely, when the semiconductor layer 320, the data line 330 and thesource and drain electrodes 333 and 336 are formed by a single maskprocess, there is the semiconductor pattern 321 under the data line 330,as shown in FIG. 14. However, if the semiconductor layer 320 is formedby a mask process different from a mask process for the data line 330and the source and drain electrodes 333 and 336, there is nosemiconductor pattern 321 under the data line 330.

The pixel electrode 355 having a plate shape is formed in each pixelregion “P” and on the gate insulating layer 315. The pixel electrode 335is formed of a transparent conductive material such as indium-tin-oxide(ITO) and indium-zinc-oxide (IZO). The pixel electrode 335 directlycontacts the drain electrode 336 and overlaps the previous gate line 305with a predetermined width. The width of the overlapped portion betweenthe pixel electrode 355 and the gate line 305 may be less than about 50percentages (%) of a width of the gate line 305.

A passivation layer 160 is formed on the data line 330, the TFT “Tr” andthe pixel electrode 355. The passivation layer 160 is formed of aninorganic insulating material, such as silicon oxide (SiO2) and siliconnitride (SiNx), or an organic insulating material, such asbenzocyclobutene (BCB) and photo-acryl. In FIGS. 14 to 15, since thepassivation layer 160 is formed an inorganic insulating material, thepassivation layer 160 has a step difference. However, when thepassivation layer 160 is formed an organic insulating material, thepassivation layer 160 has a flat top surface.

The common electrode 370 of the transparent conductive material, such asITO and IZO, is formed on the passivation layer 360 and on an entiresurface of the display region of the substrate 301. The common electrode370 has a plate shape and a plurality of openings “op” spaced apart fromeach other in each pixel region “P”. Each opening “op” has a bar shapeand has a major axis along the data line 330. There are three openings“op” in each pixel region “P”. Moreover, the openings “op” are spacedapart from each other by the same distance. However, to obtain anefficient fringe field, the common electrode 370 may have two to tenopenings “op”.

The common electrode 370 covers the TFT “Tr” in FIG. 14. However, aportion of the common electrode 370 corresponding to the TFT “Tr” may beremoved such that a portion of the passivation layer 360 is exposed.

On the second substrate 381 facing the first substrate 301, the blackmatrix 384 is formed to correspond to the data line 330 and the TFT “Tr”on the first substrate 301. The color filter layer 386 including a redcolor filter pattern 386 a, a green color filter pattern 386 b and ablue color filter pattern (not shown) and corresponding to each pixelregion “P” of the first substrate 301 is formed on the second substrate381. The overcoat layer 388 of a transparent organic insulating materialis formed on the color filter layer 386. The overcoat layer 388 has aflat top surface. The overcoat layer 388 can be omitted.

In addition, the liquid crystal layer 391 is disposed between the firstsubstrate 301 and the second substrate 381.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. An array substrate for a fringe field switching mode liquid crystaldisplay device, comprising: a plurality of gate lines on a substrate; agate insulating layer on the plurality of gate lines; a plurality ofdata lines on the gate insulating layer and crossing the plurality ofgate lines to define a plurality of pixel regions; a thin filmtransistor electrically connected to the gate and data lines and in eachpixel region; a pixel electrode having a plate shape and in the eachpixel region, the pixel electrode connected to a portion of the thinfilm transistor; a first passivation layer on the pixel electrode andover the thin film transistor; and a common electrode on the firstpassivation layer and having a plurality of openings of a bar shape inthe each pixel region, each of the openings having a major axis alongthe data line and a minor axis along the gate line, wherein a centerportion of each opening overlaps the pixel electrode, and both endsalong the major axis of each opening protrude beyond the pixelelectrode.
 2. The array substrate according to claim 1, wherein an endalong the minor axis of an outermost opening of the plurality ofopenings protrudes beyond the pixel electrode.
 3. The array substrateaccording to claim 1, wherein the pixel electrode is disposed directlyon the gate insulating layer and directly contacts the portion of thethin film transistor.
 4. The array substrate according to claim 1,further comprising a second passivation layer between the gateinsulating layer and the pixel electrode and having a contact holeexposing the portion of the thin film transistor, wherein the pixelelectrode on the second insulating layer is connected to the portion ofthe thin film transistor through the contact hole.
 5. The arraysubstrate according to claim 1, wherein the each of the openings runsacross through the pixel regions along each data line.
 6. The arraysubstrate according to claim 1, wherein the common electrode furtherincludes another opening corresponding to the thin film transistor. 7.An array substrate for a fringe field switching mode liquid crystaldisplay device, comprising: a plurality of gate lines on a substrate; agate insulating layer on the plurality of gate lines; a plurality ofdata lines on the gate insulating layer and crossing the plurality ofgate lines to define a plurality of pixel regions; a thin filmtransistor electrically connected to the gate and data lines and in eachpixel region; a pixel electrode having a plate shape and in the eachpixel region, the pixel electrode connected to a portion of the thinfilm transistor; a passivation layer on the pixel electrode and over thethin film transistor; and a common electrode on the passivation layerand having a plurality of openings of a bar shape in the each pixelregion, each of the openings having a major axis along the data line anda minor axis along the gate line, wherein a center portion of eachopening overlaps the pixel electrode, and an end along the minor axis ofan outermost opening of the plurality of openings protrudes beyond thepixel electrode.
 8. An array substrate for a fringe field switching modeliquid crystal display device, comprising: a plurality of gate lines ona substrate; a gate insulating layer on the plurality of gate lines; aplurality of data lines on the gate insulating layer and crossing theplurality of gate lines to define a plurality of pixel regions; a thinfilm transistor electrically connected to the gate and data lines and ineach pixel region; a pixel electrode having a plate shape and in theeach pixel region, the pixel electrode connected to a portion of thethin film transistor and overlapping a portion of the gate line; apassivation layer on the pixel electrode and over the thin filmtransistor; and a common electrode on the passivation layer and having aplurality of openings of a bar shape in the each pixel region, each ofthe openings having a major axis along the data line and a minor axisalong the gate line, wherein a center portion of each opening overlapsthe pixel electrode, and both ends along the major axis of each openingoverlap the gate line.
 9. The array substrate according to claim 8,wherein the overlapped portion between the each of the pixel electrodeand the gate line has a width smaller than a half of a width of the gateline.
 10. An array substrate for a fringe field switching mode liquidcrystal display device, comprising: a plurality of gate lines on asubstrate; a gate insulating layer on the plurality of gate lines; aplurality of data lines on the gate insulating layer and crossing theplurality of gate lines to define a plurality of pixel regions; a thinfilm transistor electrically connected to the gate and data lines and ineach pixel region; a pixel electrode having a plate shape and in theeach pixel region, the pixel electrode connected to a portion of thethin film transistor and overlapping a portion of the gate line; apassivation layer on the pixel electrode and over the thin filmtransistor; and a common electrode on the passivation layer and having aplurality of openings of a bar shape in the each pixel region, each ofthe openings running across through the pixel regions along each dataline.
 11. A fringe field switching mode liquid crystal display device,comprising: first and second substrate facing each other; a plurality ofgate lines on the first substrate; a gate insulating layer on theplurality of gate lines; a plurality of data lines on the gateinsulating layer and crossing the plurality of gate lines to define aplurality of pixel regions; a thin film transistor electricallyconnected to the gate and data lines and in each pixel region; a pixelelectrode having a plate shape and in the each pixel region, the pixelelectrode connected to a portion of the thin film transistor; apassivation layer on the pixel electrode and over the thin filmtransistor; a common electrode on the passivation layer and having aplurality of openings of a bar shape in the each pixel region, each ofthe openings having a major axis along the data line and a minor axisalong the gate line, wherein a center portion of each opening overlapsthe pixel electrode, and both ends along the major axis of each openingprotrude beyond the pixel electrode; a black matrix on the secondsubstrate and surrounding the each pixel region; a color filter layer onthe second substrate and corresponding to the each pixel region; and aliquid crystal layer between the first and second substrates.
 12. Thedevice substrate according to claim 11, wherein the each of the openingsruns across through the pixel regions along each data line.
 13. A fringefield switching mode liquid crystal display device, comprising: firstand second substrate facing each other; a plurality of gate lines on thefirst substrate; a gate insulating layer on the plurality of gate lines;a plurality of data lines on the gate insulating layer and crossing theplurality of gate lines to define a plurality of pixel regions; a thinfilm transistor electrically connected to the gate and data lines and ineach pixel region; a pixel electrode having a plate shape and in theeach pixel region, the pixel electrode connected to a portion of thethin film transistor; a passivation layer on the pixel electrode andover the thin film transistor; a common electrode on the passivationlayer and having a plurality of openings of a bar shape in the eachpixel region, each of the openings having a major axis along the dataline and a minor axis along the gate line, wherein a center portion ofeach opening overlaps the pixel electrode, and an end along the minoraxis of an outermost opening of the plurality of openings protrudesbeyond the pixel electrode; a black matrix on the second substrate andsurrounding the each pixel region; a color filter layer on the secondsubstrate and corresponding to the each pixel region; and a liquidcrystal layer between the first and second substrates.
 14. A fringefield switching mode liquid crystal display device, comprising: firstand second substrate facing each other; a plurality of gate lines on thefirst substrate; a gate insulating layer on the plurality of gate lines;a plurality of data lines on the gate insulating layer and crossing theplurality of gate lines to define a plurality of pixel regions; a thinfilm transistor electrically connected to the gate and data lines and ineach pixel region; a pixel electrode having a plate shape and in theeach pixel region, the pixel electrode connected to a portion of thethin film transistor and overlapping a portion of the gate line; apassivation layer on the pixel electrode and over the thin filmtransistor; a common electrode on the first passivation layer and havinga plurality of openings of a bar shape in the each pixel region, each ofthe openings having a major axis along the data line and a minor axisalong the gate line, wherein a center portion of each opening overlapsthe pixel electrode, and both ends along the major axis of each openingoverlap the gate line; a black matrix on the second substrate andshielding the data lines and the thin film transistor except the gatelines; a color filter layer on the second substrate and corresponding tothe each pixel region; and a liquid crystal layer between the first andsecond substrates.
 15. The device according to claim 14, wherein theoverlapped portion between the each of the pixel electrode and the gateline has a width smaller than a half of a width of the gate line. 16.The device substrate according to claim 14, wherein the common electrodefurther includes another opening corresponding to the thin filmtransistor.
 17. A fringe field switching mode liquid crystal displaydevice, comprising: first and second substrate facing each other; aplurality of gate lines on the first substrate; a gate insulating layeron the plurality of gate lines; a plurality of data lines on the gateinsulating layer and crossing the plurality of gate lines to define aplurality of pixel regions; a thin film transistor electricallyconnected to the gate and data lines and in each pixel region; a pixelelectrode having a plate shape and in the each pixel region, the pixelelectrode connected to a portion of the thin film transistor andoverlapping a portion of the gate line; a passivation layer on the pixelelectrode and over the thin film transistor; a common electrode on thefirst passivation layer and having a plurality of openings of a barshape in the each pixel region, each of the openings running acrossthrough the pixel regions along each data line; a black matrix on thesecond substrate and shielding the data lines and the thin filmtransistor except the gate lines; a color filter layer on the secondsubstrate and corresponding to the each pixel region; and a liquidcrystal layer between the first and second substrates.
 18. The devicesubstrate according to claim 17, wherein the common electrode furtherincludes another opening corresponding to the thin film transistor.